According to Hans-Gerd Bode, VW's top marketing man, any luxury car that wants to make it in the German market must have 'uberholprestige'. 'Autobahn drivers who see a new car's nose looming in their rear view mirror must rate the machine highly enough to pull over and let it pass.' Thanks for that. Now give me the keys and show me that autobahn…

Approaching the Phaeton, you'd be forgiven for thinking you're about to get behind the wheel of an over-sized Passat. The Phaeton is huge: 16.5' long, and 6' wide. Despite these luxo-barge dimensions, the Phaeton is elegant, in a stealth wealth, 'I'm not a Mercedes' kind of way. Understated. But not under-equipped. The Phaeton comes equipped with all the must-have luxury car toys: sat nav, on-board computer, built-in and hands-free phones, cruise control, adjustable suspension, rain sensitive wipers, five ways to change gears (automatic, sport automatic, Tiptronic, paddle shift and wheel-mounted buttons), seats that heat, cool and massage; the lot. A Golf driver wouldn't know where to start.

As I settle in, it's clear the Phaeton's 4-Zone Climatronic air con is the car's greatest contribution to automotive pampering. Air diffuses out of mesh covers on top of the dash (for the front seats), and flows out of the pillar between the side windows (for the rear seats). If the cabin requires radical heating or cooling, part of the wooden fascia retracts to exposes traditional vents. Once the cabin reaches the correct temperature, the fascia slides back and resumes indirect temperature control. Cool.

Which is a good thing to be when you're powering down the A2 autobahn to Dresden at a rock-steady 145mph. Actually, once you get used to watching trucks zip backwards as if fired from a rifle, it's no big deal. The Phaeton is a completely composed autobahnstormer: quiet, solid and supremely comfortable. And fast. Drop it into Sport, and the mildest throttle provocation catapults the VW leviathan at the horizon with seamless, relentless oomph- no matter what the original speed.

The Phaeton VW lent me was powered by VW's new W12. It's the world's most compact 12-cylinder engine, developing 420bhp at 6000rpms. The 6.0-litre power plant also generates a massive 406ft lbs of torque at 3000rpms. That's enough low-down grunt to propel Volkswagen's biggest ever car from zero to sixty miles per hour in a shade over six seconds, or, if you prefer, up to an electronically limited 155mph.

Except my demonstrator was no castrato. After a day of acclimation, I pushed the beast to 260kmh (165.1mph). At those speeds, the Phaeton parts slower traffic like Moses gesturing at the Red Sea. Even Porsche Carreras submit to the Phaeton's massive, thrusting prow. In a country that builds the world's most powerful sedans (I watched an M5 streak past at 185+), a Volkswagen can mix it with the big boys.

Just don't get too frisky in the corners. At 2.5 tons, most of which lives north of the front wheels, the Phaeton is genetically predisposed to terminal understeer. The steering is light enough to power a helium balloon. That said, the brakes are superb. The handling is safe and predictable. Once the car settles into a bend, it remains stable. If you carry too much speed into the twisty bits, traction control and four-wheel drive will do everything in their power to prevent an off-road excursion.

But not even adjustable shocks, air suspension and 18' tires can re-write the laws of physics. It's best keep in mind that the word 'Phaeton' comes from the Greek myth of Phaethon, a young man killed by Zeus' thunderbolt after running amok with his Dad's sun chariot. The Phaeton's Queen Mary driving dynamics are perhaps the least surprising thing about the car. Volkswagen is hardly the company you'd expect to take on BMW's 7-Series and Mercedes' S Class. VW was born to build millions of sensible automobiles for millions of sensible drivers. A Volkswagen four-door that costs between £43k (V6) and £70k (W12) seems about as likely-and marketable- as a Rolls Royce bread van. Besides, the VW group makes the Audi A8 and forthcoming Bentley four-door to compete for the luxury car dollar. Surely someone somewhere has lost the plot…

Only time will tell. One thing is for sure: the Volkswagen Phaeton is aimed straight at the soft underbelly of US luxury car buyers. The majority of these customers aren't interested in the Phaeton's 'uberholprestige', cornering prowess, or lack thereof. They simply want to know if the Phaeton offers a viable alternative to its more expensive European and Japanese rivals. That it does. The Phaeton offers extreme levels of sybaritic luxury. Pistonheads and badge snobs need not apply, but the Phaeton is a wundercar.